CVE-2023-28803: Traffic being bypassed by ZCC by configuring synthetic IP range as local network

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2023-10-23 · updated 2026-06-17
Weakness: CWE-290

Description

An authentication bypass by spoofing of a device with a synthetic IP address is possible in Zscaler Client Connector on Windows, allowing a functionality bypass. This issue affects Client Connector: before 3.9.

Affected products

Zscaler Client Connector: before 3.9 — fixed in 3.9

How to fix

Upgrade to a fixed version: Zscaler Client Connector 3.9. Check the vendor advisory for mitigations.

References

https://help.zscaler.com/client-connector/client-connector-app-release-summary-2023
https://help.zscaler.com/client-connector/client-connector-app-release-summary-2023

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